This invention relates to a method and an inspection catheter for easy and safe fixation of pervenous electrodes at the optimum position within the right atrium for treatment of arrhythmia through the electrical stimulation of the affected heart.
The pacemakers of the kind which require that electrodes for delivering rhythmical electrical stimuli be fixed within the atrium include the P-synchronized pacemaker, the bifocal demand pacemaker, the fixed-rate pacemaker, the demand pacemaker and the radio-frequency induced atrial pacemaker.
The electrodes for delivering electrical stimulating pulses from pacemakers to the atrium are broadly grouped by the method of fixation thereof into two types: Myocardial electrodes which are fixed as by thoracotomy and allowed to generate electrical stimuli epicardially and pervenous electrodes which are fixed after insertion through the incised subclavian vein and allowed to generate electrical stimuli endocardially. The myocardial electrodes are highly susceptible to surgical incursions and, therefore, are not suitable for use on senile patients and poor risk patients unable to endure surgery. The present invention relates to a method for the endocardial stimulation by use of a pervenous electrode.
The methods which have heretofore been developed for the fixation of pacemaker pervenous electrodes in the right atrium include those involving insertion of a J-shaped lead or anchored electrodes in the right atrial appendages and those involving insertion of a pair of pacemaker pervenous electrodes in the coronary sinuses, for example. In all these conventional methods, since the electrodes are not sutured to the endocardium, there is a possibility of the electrodes being detached from the positions of the endocardium where they were initially fixed, with the result that the pacemakers will fail to provide required pacing and sensing actions.
The inventor, therefore, performed clinical trials in search of a way of improving the conventional methods described above. On the basis of the outcomes of the clinical trials, the inventor perfected a method for safe fixation of the pervenous electrodes at the optimum position within the right atrium to provide required atrial pacing in a given case. At the 30th general meeting of the Japanese Association for Thoracic Surgery held on Sept. 25, 1977, the inventor published this method. He further published this method in medical journals, specifically in the February, 1978 and August, 1978 issues of the "Japanese Journal of Thoracic Surgery" and in the "Journal of the Japanese Association for Thoracic Surgery", Vol. 26, No. 8.
The gist of the publication is as follows:
The subclavian fossa of a given patient is subjected to skin incision to expose the right cepharic vein and a catheter with a pair of inspection electrodes for potential detection is inserted through the vein into the right atrium. The right atrium is explored with the inserted catheter to determine the optimum position of a permanent pervenous pacemaker electrode through measurement of the stimulating thresholds and endocardial potentials in the anterior and lateral walls inside the right atrium. When the optimum position for fixing the pacemaker electrode is found, the catheter for potential detection is extracted. Then in the same manner, a guide catheter consisting of an outer tube and guidewire slidably built in the outer tube is inserted into the right atrium. The rear end of the guidewire is pushed into the outer tube to form at the predetermined optimum position a loop of the guidewire at the leading end of the outer tube under fluoroscopic observation. Thereafter, a double lumen needle is pierced through the chest wall in the direction of the formed loop of the guidewire inside the right atrium under fluoroscopic observation. After a doubly folded fine steel wire is inserted into the right atrium through the double lumen needle, the guidewire is drawn back through the outer tube to contract the loop of the guidewire thereby to catch firm hold of the inserted end of the steel wire and then, the guide catheter is extracted together with the steel wire. The guide catheter thus extracted is released from the steel wire and instead, the pervenous pacemaker electrode is connected to the steel wire by means of a sutural thread. The steel wire is next caused to introduce the pacemaker electrode into the interior of the right atrium by pulling outwardly the rear ends of the steel wire remaining the outer side of the lumen needle so as to pull the sutural thread out of the lumen needle. When the pacemaker electrode reaches the predetermined optimum position, the double lumen needle is removed from the chest wall and the sutural thread is sutured on the subcutaneous tissue for thereby fixing the pacemaker electrode in the endocardium of the atrium. Even this method unfortunately requires more time and labor and higher surgical skill.
An object of the present invention, therefore, is to provide a method and an inspection catheter for ready fixation of the pervenous pacemaker electrode at the optimum position within the atrium, with ample saving in the time and labor required for the fixation of the pacemaker electrode in the endocardium in the atrial pacing.